1. Field of the Invention
The present invention relates to electronic sensor systems, electronics and networks capable of operating in high-temperature environments.
2. Technical Background
A number of systems that require or benefit from automated electronic monitoring or control operate at elevated temperatures. Examples of such systems include the engines of aircraft and automobiles, vehicle frames, refineries, nuclear and chemical plants, and in downhole drilling for petroleum, natural gas and the like. Elevated temperatures can create inhospitable environments for the electronics associated with sensors used in control and monitoring systems because the bandgap of semiconductor materials decreases as a function of temperature, resulting in performance degradation at higher temperatures. Conventional electronics fabricated in bulk silicon typically have an upper temperature limit of about 70° C., or 125° C. for military applications. Elevated-temperature systems that use conventional electronics typically do so by packaging the electronics with heat sinks or active cooling devices, which add weight and increase system complexity, or by distancing the electronic components from “hot zones” (i.e., high-temperature regions) where sensors reside by adding cabling between sensors and their associated electronics, which both adds weight and can add noise to signals obtained from sensors.
In many modern aircraft, and particularly in military aircraft, engine parameters are monitored and engine controls are adjusted by a full authority digital engine control (FADEC) system. Typically built into an enclosure roughly the size of a shoebox, a FADEC is a computerized unit with sensor inputs and actuator outputs that works to govern engine fuel flow, variable engine geometrics and various other controls to ensure the performance, safety and efficiency of the propulsion unit. A FADEC eliminates direct mechanical linkages between pilot controls (e.g., the throttle) and an engine, and in doing so, achieves more optimal performance in all phases of flight while taking into account the operational limits of the engines in order to reduce the probability of failure. On military aircraft, FADECs also protect against electromagnetic radiation after a nuclear explosion or the like by quickly switching off electronic control systems upon the detection of radiation. As with all aircraft parts, it is desirable that a FADEC be lightweight, but some FADECs for civil applications can weigh as much as 27 kg. Military FADECs typically weigh no more than 13 kg. The temperature-dependent reliability of electronic components contained within a FADEC, such as microprocessors, means that FADECs must be mounted away from hot zones on aircraft propulsion systems and often must be supported by costly, heavy, and expensive cooling systems.
It is therefore the object of the present invention to provide a sensor interface that would act as an intermediary between inputs (e.g., sensors) and the electronic control system accepting those inputs and supplying output signals (e.g., to actuators and switches), or that would act as an intermediary between inputs and a monitor. It is further an object of the present invention to provide a sensor interface that permits its placement in hot zones closer to the sensors with which it would interface. It is further an object of the present invention to provide a sensor interface or network that provides the benefits of increased noise immunity, increased reliability, decreased cost, reduced weight, and reduced space required in automated systems.